A pincer gripper system can comprise a gripper tube, for example, on which preferably spring-mounted pincer halves (strikes) are mounted, and a pincer gripper shaft, which is mounted coaxially, in particular, inside said gripper tube. Fixed pincer halves (tongues) can be screw-mounted on the pincer gripper shaft. Due to space considerations, it is customary to mount the pincer gripper shaft using space-saving sliding bearing sleeves, which are adhesively bonded into the gripper tube or onto the pincer gripper shaft. The bearing points of the gripper tube that are located at the same positions are also typically formed using sliding bearing sleeves, to keep the bearing points from protruding too far out of the drum body.
Known from DE-OS 2414998 is a turning device for a perfecting printing machine having pincer grippers, in which the pincer gripper shaft is mounted in sliding bearings.
DE 10 2005 045289 A1 discloses a sliding surface mounting, in which the pincer gripper shaft is mounted over a cast resin bearing surface.
It is a disadvantage that adequate functional clearance and sufficient lubricant are extremely critical for the functioning of the sliding bearing arrangement. Any deformation of the coaxial shafts or insufficient lubrication can result in increased wear on the bearing.
DE 103 50 987 A1 discloses a gripper system in a sheet-guiding cylinder of a sheet-fed rotary printing machine, in which a gripper shaft is mounted rotatably directly on the sheet-guiding cylinder, and a swinger shaft is composed of gripper boxes, rotatably mounted separately on the gripper shaft. The disadvantage of this solution is that the gripper shaft is still mounted on a plurality of bearing supports of the cylinder. The swinger shaft composed of gripper boxes thus has a complex construction.
With pincer gripper systems, the space conditions are too tight for known rolling bearing arrangements. Furthermore, the hardened raceways that are required cannot be produced within the necessary form and position tolerances.